A preparation method of a sodium alginate-based hydrogel composite membrane for adsorbing lead ions

Abstract

The present application relates to a kind of preparation method of sodium alginate-based hydrogel composite membrane for adsorbing lead ions, belong to heavy metal ion adsorbent preparation field, the method is first using thiol-containing silane coupling agent to functionalize porous material, obtain thiol-functionalized porous material;Then the thiol-functionalized porous material is mixed with urea, sodium alginate to obtain sodium alginate-based hydrogel synthesis fluid;Again it is poured into the crosslinking agent solution super flat culture dish in and carries out crosslinking, finally obtain sodium alginate-based hydrogel composite membrane.The introduction of thiol-functionalized porous material in the method not only enhances the mechanical strength and stability of sodium alginate hydrogel, but also can significantly improve heavy metal ion adsorption capacity.The method has low requirement to equipment, mild reaction condition, low cost;Prepared hydrogel composite membrane is non-toxic harmless, easy to recycle, and has excellent adsorption performance, is suitable for industrial large-scale application.

Description

Technical Field

[0001] This invention belongs to the field of agricultural machinery technology, and in particular relates to a method for preparing a sodium alginate-based hydrogel composite membrane for adsorbing lead ions. Background Technology

[0002] Adsorption is an important method for removing heavy metal ions from aqueous solutions, widely used due to its simplicity, efficiency, and low cost. Common adsorbent materials include metal oxides, natural polymers, porous carbon materials, and molecular sieves. Sodium alginate, a natural anionic polysaccharide, is widely available and inexpensive, typically obtained from algae and certain bacteria. Sodium alginate is mainly composed of β-D-mannuronic acid (M unit) and α-L-guluronic acid (G unit). The G unit contains Na... + It can undergo displacement reactions with other metal cations to obtain hydrogels with a three-dimensional network structure. Based on this, introducing other materials with metal adsorption capabilities can yield hydrogel composite membranes with high adsorption capacity. This modification method not only improves the stability, biocompatibility, and recyclability of pure organic ligands but also enhances the strength of the hydrogel. Bai et al. prepared a graphene oxide / sodium alginate hydrogel composite membrane using graphene oxide as a dopant to remove lead ions from aqueous solutions (International Journal of Biological Macromolecules, 2020, 147: 898-910). Currently, improvements in the preparation methods of sodium alginate-based hydrogel composite membranes mainly involve doping with materials of different specific surface areas and pore sizes to improve their adsorption performance, but the improvement in adsorption capacity is limited. To date, there is limited research on optimizing the coordination of functional groups on the surface of doped materials with lead ions, failing to truly reflect the diversity and tunability of the surface properties of doped materials in sodium alginate-based hydrogel composite membranes. Therefore, developing a sodium alginate-based hydrogel composite membrane with a simple synthesis method and good adsorption effect on lead ions has good application prospects. Summary of the Invention

[0003] To address the aforementioned technical problems, a method for preparing a sodium alginate-based hydrogel composite membrane for adsorbing lead ions is provided. The sodium alginate-based hydrogel composite membrane synthesized by this method not only has good stability and biocompatibility, but also achieves efficient adsorption of lead ions in water by utilizing thiol-functionalized porous materials doped in the hydrogel composite membrane.

[0004] The objective of this invention is achieved through the following technical solution:

[0005] This invention discloses a method for preparing a sodium alginate-based hydrogel composite membrane for adsorbing lead ions, the specific steps of which are as follows:

[0006] (1) Preparation of thiol-functionalized porous materials:

[0007] 1 g to 5 g of porous material was dispersed in 60 mL to 200 mL of organic solvent, and 1 g to 5 g of silane coupling agent was added to the above solution. After stirring in an inert atmosphere at a reaction temperature of 60 ℃ to 120 ℃ for 12 h to 48 h, the mixture was filtered, washed, and dried for 6 to 24 hours to obtain thiol-functionalized porous material.

[0008] (2) Preparation of hydrogel synthesis solution:

[0009] Weigh 1 g to 5 g of the thiol-modified porous material obtained in step (1), add it to 50 mL to 200 mL of deionized water and sonicate for 5 min to 30 min. Then add 2 g to 8 g of urea and 2 g to 10 g of sodium alginate to the above solution after treatment, stir for 12 h to 48 h, and let stand for 2 h to 12 h to obtain a uniform and viscous synthetic solution.

[0010] (3) Preparation of sodium alginate-based hydrogel composite membrane:

[0011] Place 10 g to 30 g of the synthesis solution obtained in step (2) in an ultraflat culture dish with a diameter of 4 cm to 10 cm and let it stand for 4 h to 24 h. Then dry it for 8 h to 24 h to form a membrane material. After curing the membrane material in 50 mL to 200 mL of crosslinking agent solution for 12 h to 48 h, wash the obtained hydrogel composite membrane with deionized water 3 to 10 times and dry it for 6 h to 48 h to obtain a sodium alginate-based hydrogel composite membrane.

[0012] Furthermore, the porous material in step (1) is SBA-15 molecular sieve, chitosan, MCM-41 molecular sieve, graphene oxide, activated carbon, or UIO-66.

[0013] Furthermore, the organic solvent in step (1) is methanol or ethanol.

[0014] Further, the silane coupling agent in step (1) is one of (3-mercaptopropyl)trimethoxysilane, (3-mercaptopropyl)triethoxysilane, or 3-mercaptopropyl(dimethoxy)silane.

[0015] Furthermore, the inert atmosphere in step (1) is either nitrogen or argon.

[0016] Furthermore, the drying temperature in step (1) is 80 ℃~120 ℃.

[0017] Furthermore, the stirring temperature in step (2) is 20 ℃~50 ℃.

[0018] Furthermore, the crosslinking agent solution in step (3) is a calcium chloride solution, a ferrous chloride solution, or a zinc chloride solution.

[0019] Furthermore, the concentration of the crosslinking agent solution in step (3) is 10 g / L to 50 g / L.

[0020] Furthermore, the drying temperature in step (3) is 40 ℃~100 ℃.

[0021] The beneficial effects of this invention are as follows:

[0022] This invention involves thoroughly mixing a thiol-functionalized porous material, urea, and sodium alginate, then using a crosslinking agent to form a three-dimensional network structure to obtain a hydrogel composite membrane. This method not only enhances the mechanical strength and stability of the sodium alginate-based hydrogel but also endows it with excellent adsorption properties. The method requires minimal equipment, operates under mild reaction conditions, and is low-cost; the prepared hydrogel composite membrane is non-toxic, harmless, and suitable for industrial applications. Attached Figure Description

[0023] Figure 1 This is a cross-sectional SEM image of the sodium alginate-based hydrogel composite membrane in this invention.

[0024] Figure 2 This is the FT-IR image of the sodium alginate-based hydrogel composite membrane in this invention.

[0025] Figure 3 This is the XRD pattern of the sodium alginate-based hydrogel composite membrane in this invention.

[0026] Figure 4 This is a graph showing the lead ion adsorption performance of the sodium alginate-based hydrogel composite membrane in this invention. Detailed Implementation

[0027] The present invention will now be described in detail with reference to the accompanying drawings and embodiments.

[0028] Example 1, (1) Synthesis of thiol-functionalized SBA-15 molecular sieve:

[0029] 1 g of SBA-15 molecular sieve was dispersed in 100 mL of anhydrous methanol, and 1 g of 3-mercaptopropyl(dimethoxy)silane was added to the above solution. After stirring at 60 °C under a nitrogen atmosphere for 12 h, the mixture was filtered, washed, and dried at 80 °C for 24 h to obtain thiol-functionalized SBA-15 molecular sieve.

[0030] (2) Preparation of hydrogel synthesis solution:

[0031] Weigh 1 g of the thiol-functionalized SBA-15 molecular sieve obtained in step (1), add 50 mL of deionized water and sonicate for 5 min, then add 2 g of urea and 2 g of sodium alginate to the above solution in sequence, stir at 20 ℃ for 12 h, let stand for 2 h, and obtain a uniform and viscous synthetic solution.

[0032] (3) Preparation of sodium alginate-based hydrogel composite membrane:

[0033] 10 g of the synthetic solution obtained in step (2) was placed in an 8 cm diameter ultraflat culture dish and left to stand for 4 h. Then it was dried at 40 ℃ for 8 h to form a membrane material. The membrane material was placed in 50 mL of calcium chloride solution with a concentration of 10 g / L and cured for 12 h. The resulting hydrogel composite membrane was washed three times with deionized water and dried at 40 ℃ for 6 h to obtain a sodium alginate-based hydrogel composite membrane.

[0034] Example 2, (1) Synthesis of thiol-functionalized chitosan:

[0035] 2.5 g of chitosan was dispersed in 60 mL of anhydrous ethanol, and 3 g of (3-mercaptopropyl)triethoxysilane was added to the solution. After stirring at 90 °C under an argon atmosphere for 24 h, the mixture was filtered, washed, and dried at 90 °C for 12 h to obtain thiol-functionalized chitosan.

[0036] (2) Preparation of hydrogel synthesis solution:

[0037] Weigh 2.5 g of the thiol-functionalized chitosan obtained in step (1), add it to 100 mL of deionized water and sonicate for 15 min. Then add 4 g of urea and 6 g of sodium alginate to the above solution in sequence, stir at 30 °C for 24 h, and let stand for 4 h to obtain a uniform and viscous synthetic solution.

[0038] (3) Preparation of sodium alginate-based hydrogel composite membrane:

[0039] 15 g of the synthesis solution obtained in step (2) was placed in a 6 cm diameter ultraflat culture dish and left to stand for 12 h. The solution was then dried at 60 °C for 12 h to form a membrane material. The membrane material was then placed in 100 mL of 30 g / L ferrous chloride solution and cured for 24 h. The resulting hydrogel composite membrane was then washed 6 times with deionized water and dried at 60 °C for 12 h to obtain a sodium alginate-based hydrogel composite membrane.

[0040] Example 3, (1) Synthesis of mercapto-modified MCM-41 molecular sieve:

[0041] 4 g of SBA-15 molecular sieve was dispersed in 180 mL of anhydrous methanol, and 3 g of (3-mercaptopropyl)triethoxysilane was added to the above solution. After stirring at 100 °C under nitrogen for 36 h, the mixture was filtered, washed, and dried at 100 °C for 18 h to obtain thiol-functionalized MCM-41 molecular sieve.

[0042] (2) Preparation of hydrogel synthesis solution:

[0043] Weigh 4g of the thiol-functionalized MCM-41 molecular sieve obtained in step (1), add 150mL of deionized water and sonicate for 20min. Then add 6g of urea and 8g of sodium alginate to the above solution in sequence, stir at 35℃ for 36h, and let stand for 10h to obtain a uniform and viscous synthetic solution.

[0044] (3) Preparation of sodium alginate-based hydrogel composite membrane:

[0045] 20 g of the synthesis solution obtained in step (2) was placed in a 4 cm diameter ultraflat culture dish and left to stand for 18 h. Then it was dried at 80 ℃ for 24 h to form a membrane material. The membrane material was placed in 150 mL of calcium chloride solution with a concentration of 20 g / L and cured for 36 h. The resulting hydrogel composite membrane was washed with deionized water 8 times and dried at 70 ℃ for 36 h to obtain a sodium alginate-based hydrogel composite membrane.

[0046] Example 4, (1) Synthesis of thiol-functionalized graphene oxide:

[0047] 5 g of graphene oxide was dispersed in 200 mL of anhydrous ethanol, and 5 g of (3-mercaptopropyl)trimethoxysilane was added to the solution. After stirring at 120 °C under a nitrogen atmosphere for 48 h, the mixture was filtered, washed, and dried at 120 °C for 6 h to obtain mercapto-functionalized graphene oxide.

[0048] (2) Preparation of hydrogel synthesis solution:

[0049] Weigh 5 g of the thiol-functionalized graphene oxide obtained in step (1), add 200 mL of deionized water and sonicate for 30 min. Then add 8 g of urea and 10 g of sodium alginate to the above solution in sequence, stir at 50 °C for 48 h, and let stand for 12 h to obtain a uniform and viscous synthetic solution.

[0050] (3) Preparation of sodium alginate-based hydrogel composite membrane:

[0051] 30 g of the synthesis solution obtained in step (2) was placed in a 10 cm diameter ultraflat culture dish and left to stand for 24 h. Then it was dried at 100 ℃ for 24 h to form a membrane material. The membrane material was placed in 200 mL of 50 g / L zinc chloride solution and cured for 48 h. The resulting hydrogel composite membrane was washed 10 times with deionized water and dried at 100 ℃ for 48 h to obtain a sodium alginate-based hydrogel composite membrane.

[0052] Example 5, (1) Synthesis of thiol-functionalized activated carbon:

[0053] 2 g of activated carbon was dispersed in 120 mL of anhydrous ethanol, and 2 g of (3-mercaptopropyl)triethoxysilane was added to the solution. After stirring at 100 °C under a nitrogen atmosphere for 24 h, the mixture was filtered, washed, and dried at 120 °C for 8 h to obtain thiol-functionalized activated carbon.

[0054] (2) Preparation of hydrogel synthesis solution:

[0055] Weigh 4 g of the thiol-functionalized activated carbon obtained in step (1), add 100 mL of deionized water and sonicate for 20 min. Then add 4 g of urea and 4 g of sodium alginate to the above solution in sequence, stir at 30 °C for 36 h, and let stand for 12 h to obtain a uniform and viscous synthetic solution.

[0056] (3) Preparation of sodium alginate-based hydrogel composite membrane:

[0057] 20 g of the synthesis solution obtained in step (2) was placed in an ultraflat culture dish with a diameter of 8 cm and left to stand for 12 h. Then it was dried at 60 ℃ for 12 h to form a membrane material. The membrane material was placed in 100 mL of calcium chloride solution with a concentration of 30 g / L and cured for 36 h. The resulting hydrogel composite membrane was washed with deionized water 8 times and dried at 60 ℃ for 24 h to obtain a sodium alginate-based hydrogel composite membrane.

[0058] Example 6, (1) Synthesis of thiol-functionalized UIO-66:

[0059] 4 g of UIO-66 was dispersed in 200 mL of anhydrous methanol, and 2 g of 3-mercaptopropyl(dimethoxy)silane was added to the solution. After stirring at 80 °C under an argon atmosphere for 12 h, the mixture was filtered, washed, and dried at 90 °C for 10 h to obtain thiol-functionalized UIO-66.

[0060] (2) Preparation of hydrogel synthesis solution:

[0061] Weigh 1 g of the thiol-functionalized UIO-66 obtained in step (1), add 200 mL of deionized water and sonicate for 10 min. Then add 8 g of urea and 10 g of sodium alginate to the above solution in sequence, stir at 40 °C for 12 h, and let stand for 8 h to obtain a uniform and viscous synthetic solution.

[0062] (3) Preparation of sodium alginate-based hydrogel composite membrane:

[0063] 15 g of the synthesis solution obtained in step (2) was placed in a 10 cm diameter ultraflat culture dish and left to stand for 8 h. Then it was dried at 50 °C for 24 h to form a membrane material. The membrane material was placed in 100 mL of 50 g / L ferrous chloride solution and cured for 24 h. The resulting hydrogel composite membrane was washed 10 times with deionized water and dried at 50 °C for 24 h to obtain a sodium alginate-based hydrogel composite membrane.

[0064] Example 7: The specific steps of the adsorption experiment of lead ions by the sodium alginate-based hydrogel composite membrane prepared by the present invention are as follows: Sodium alginate-based hydrogel composite membranes with an area of ​​1 cm × 1 cm obtained in Examples 1, 2, 3, 4, 5, and 6 were respectively placed in 50 mL of a 300 mg / L lead ion solution and adsorbed at 40°C for 4 hours. Then, the supernatant was taken, and the concentration of residual lead ions was measured using atomic absorption spectrometry. The adsorption capacity of the sodium alginate-based hydrogel composite membrane for lead ions was calculated, and the results are shown in Table 1. Analysis of Table 1 shows that the sodium alginate-based hydrogel composite membrane obtained according to the technical solution provided by the present invention has high adsorption performance for lead ions.

[0065] Table 1. Adsorption performance of sodium alginate-based hydrogel composite membrane for lead ions:

[0066]

[0067] It is understood that the above specific description of the present invention is only for illustrating the present invention and is not limited to the technical solutions described in the embodiments of the present invention. Those skilled in the art should understand that modifications or equivalent substitutions can still be made to the present invention to achieve the same technical effect; as long as the use needs are met, they are all within the protection scope of the present invention.

Claims

1. A method for preparing a sodium alginate-based hydrogel composite membrane for adsorbing lead ions, characterized in that: The specific steps are as follows: (1) Preparation of thiol-functionalized porous materials: 1 g to 5 g of porous material was dispersed in 60 mL to 200 mL of organic solvent. The porous material was SBA-15 molecular sieve, chitosan, MCM-41 molecular sieve, graphene oxide, activated carbon, or UIO-66. 1 g to 5 g of silane coupling agent was added to the above solution. The silane coupling agent was one of (3-mercaptopropyl)trimethoxysilane, (3-mercaptopropyl)triethoxysilane, or 3-mercaptopropyl(dimethoxy)silane. After stirring in an inert atmosphere at a reaction temperature of 60 °C to 120 °C for 12 h to 48 h, the mixture was filtered, washed, and dried for 6 to 24 hours at a drying temperature of 80 °C to 120 °C to obtain the thiol-functionalized porous material. (2) Preparation of hydrogel synthesis solution: Weigh 1 g to 5 g of the thiol-modified porous material obtained in step (1), add it to 50 mL to 200 mL of deionized water and sonicate for 5 min to 30 min. Then add 2 g to 8 g of urea and 2 g to 10 g of sodium alginate to the above solution after treatment, stir for 12 h to 48 h, and let stand for 2 h to 12 h to obtain a uniform and viscous synthetic solution. (3) Preparation of sodium alginate-based hydrogel composite membrane: Place 10 g to 30 g of the synthesis solution obtained in step (2) in an ultraflat culture dish with a diameter of 4 cm to 10 cm and let it stand for 4 h to 24 h, then dry it for 8 h to 24 h to form a membrane material; put the membrane material into 50 mL to 200 mL of crosslinking agent solution to cure for 12 h to 48 h, then wash the obtained hydrogel composite membrane with deionized water 3 to 10 times and dry it for 6 h to 48 h to obtain a sodium alginate-based hydrogel composite membrane with a three-dimensional network structure; The crosslinking agent solution is a calcium chloride solution, a ferrous chloride solution, or a zinc chloride solution.

2. The method for preparing the sodium alginate-based hydrogel composite membrane for adsorbing lead ions according to claim 1, characterized in that: The organic solvent in step (1) is methanol or ethanol.

3. The method for preparing the sodium alginate-based hydrogel composite membrane for adsorbing lead ions according to claim 1, characterized in that: The inert atmosphere in step (1) is either nitrogen or argon.

4. The method for preparing a sodium alginate-based hydrogel composite membrane for adsorbing lead ions according to claim 1, characterized in that: The stirring temperature in step (2) is 20 ℃~50 ℃.

5. A method for preparing a sodium alginate-based hydrogel composite membrane for adsorbing lead ions according to claim 1, characterized in that: The concentration of the crosslinking agent solution in step (3) is 10 g / L to 50 g / L.

6. A method for preparing a sodium alginate-based hydrogel composite membrane for adsorbing lead ions according to claim 1, characterized in that: The drying temperature in step (3) is 40 ℃~100 ℃.

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